Oxycombustion Flame Control via Inert Gas Swirl Injection
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Solution Overview
Problem
Conventional combustion devices using air as an oxidizer are not suitable for high-oxygen or all-oxygen combustion due to geometry and material limitations, and flue gas recycling methods often nullify the benefits of oxycombustion, such as increased unburnts and ash complications in downstream flue gas treatment.
Innovation Solution
A combustion method using an oxygen-containing gas with at least 80% oxygen, where the fuel and oxygen gas are injected to create a flame, and a mainly inert gas, such as recycled flue gas, is injected surrounding the flame with a divergent swirl to control flame size and temperature, allowing for flexible operation between oxycombustion and air combustion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If flue gas is reinjected to compensate for nitrogen absence in oxycombustion, then NOx production is reduced, but the benefits of oxycombustion (lower unburnts and ash) are nullified
Solution Approach 1:
The invention changes the chemical composition parameters of the oxidizer by using oxygen-enriched air (21-80% oxygen) instead of conventional air (21% oxygen), and controls the flue gas recirculation ratio to maintain combustion efficiency while reducing NOx formation through parameter optimization
Solution Approach 2:
The invention applies partial flue gas recirculation (not complete recirculation) to achieve a balance between NOx reduction and maintaining combustion efficiency, using just enough recirculated flue gas to control thermal NOx formation without completely nullifying the benefits of oxycombustion
2Ease of manufacture
If flue gas is mixed with oxygen before burner introduction, then air burners can be retained with minor adjustments, but safety problems arise from premixing
Solution Approach 1:
The invention segments the oxidizer supply into two separate streams: primary oxygen-enriched air for combustion and recirculated flue gas for temperature control, allowing conventional burners to be retained while avoiding dangerous premixing of fuel and high-concentration oxygen
Solution Approach 2:
The invention uses oxygen-enriched air as an intermediary medium that provides the benefits of high-oxygen combustion while maintaining the safety characteristics of conventional air combustion systems, avoiding direct premixing of pure oxygen with fuel
3Length of moving object
If flue gas is injected at high velocity to control flame length, then flame size is reduced, but combustion chamber elements are overheated
Solution Approach 1:
The invention changes the velocity parameter of flue gas injection to an optimized range that achieves adequate flame length control without causing excessive heat transfer to combustion chamber walls, balancing flame containment with thermal management
4Temperature
If flue gas injection velocity is reduced to prevent overheating, then combustion chamber elements are protected, but burner size increases and layout problems occur
Solution Approach 1:
The invention optimizes the flue gas injection velocity parameter to a specific range that provides adequate flame control without excessive heat transfer, avoiding both overheating and the need for oversized burners
5Ease of manufacture
If conventional air combustion is used, then burner geometry and materials are sufficient, but CO2 emissions and NOx production are high
Solution Approach 1:
The invention changes the oxidizer composition parameter from conventional air (21% oxygen) to oxygen-enriched air (21-80% oxygen), achieving reduced CO2 emissions through more efficient combustion while maintaining burner compatibility through gradual parameter transition
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method produces a flame with a controlled size and high core temperature, reducing unburnts and enabling efficient operation in confined vessels like boilers, while maintaining safety and minimizing ash complications in flue gas treatment.
Implementation Method 1
the said mainly inert gas is injected in such a way that it is contiguous to and surrounds the flame created by the said fuel and the said oxygen containing gas and that it has a divergent swirl with regard to the flame
Implementation Method 2
the said mainly inert gas is injected in such a way that it is contiguous to and surrounds the flame
Implementation Method 3
the said fuel and the said oxygen containing gas are injected in such a way as to create a flame
Data Source
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AI summary
The invention relates to a method of combustion of a fuel using an oxygen containing gas and at least one mainly inert gas, in which: - the said oxygen containing gas comprises at least 80% of oxygen in volume, - the said fuel and the said oxygen containing gas are injected in such a way as to create a flame, - the said mainly inert gas is injected in such a way that it is contiguous to and surrounds the flame created by the said fuel and the said oxygen containing gas and that it has a divergent swirl with regard to the flame.